1. Field of the Invention
The present invention relates in general to automotive speedometer drive gearing within a transaxle and more particularly to the speedometer drive gear arrangement thereof.
2. Description of the Prior Art
FIG. 5 shows a prior art speedometer drive gear arrangement of the kind wherein a worm gear made of a synthetic resinous or plastic material is used as a take-off gear for driving an automotive speedometer.
Referring to FIG. 5, a plastic worm gear 22' of the overall thickness A' is mounted on a differential case 18' and fixedly attached thereto by being clamped at axial end faces 22'c and 22'd between the shoulder 18'b in the differential case 18' and the inner race of a bearing 24'.
The prior art speedometer drive gear arrangement of the above described kind has the disadvantage that the worm gear 22' tends to be distorted or become loose when the temperature of the worm gear varies due to the fairly large difference in thermal expansion or contraction coefficient between the plastic material forming the worm gear 22' and the iron or steel forming the differential case 18' causing troubles in operation of the speedometer.